The program is aimed at elucidating the mechanisms that regulate pituitary and adrenocortical secretion. Particular attention is being paid to defining the mechanisms that regulate renin secretion, the effects of angiotensin on the brain, and the role of the angiotensin-generating enzyme and related components to the renin-angiotensin system in the brain. Studies of the effects of catecholamines on ACTH secretion are also being carried out to delineate the central adrenergic pathway which inhibits ACTH secretion, and similar studies of growth hormone secretion are under way. The program also provides partial support for research on the mechanisms responsible for the circhoral fluctuations in plasma LH secretion. BIBLIOGRAPHIC REFERENCES: Ganong, W. F., N. Kramer, J. Salmon, I. A. Reid, R. Lovinger, U. Scapagnini, A. T. Boryczka and R. Shackelford. Pharmacological evidence for inhibition of ACTH secretion by a central noradrenergic system in the dog. Neuroscience 1:167-174, 1976. Rabii, J. and W. F. Ganong. Responses of plasma "estradiol" and plasma LH to ovariectomy, ovariectomy plus adrenalectomy, and estrogen injection at various ages. Neuroendocrinology 20:270-281, 1976.